Diodes
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In a circuit with an alternating current, a diode lets forward current through, but it blocks the reverse current. This is called rectifying the current.
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Types of diodes
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The first diodes were vacuum tube devices (also known as thermionic valves), arrangements of electrodes surrounded by a vacuum within a glass envelope, similar in appearance to incandescent light bulbs.
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Lamps
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Turn electrical energy into heat energy and produce light. Various types of lamps are used in the automobile.
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Resistors
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Resistors are used to cause a drop in voltage in circuits. They are used to control current flow.
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Resistor ratings
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To identify its value, each resistor is marked with four or five colored bands. Each color represents a number value, so by reading the color values it is possible to identify its resistance value.
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Variable resistors
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Some resistors found in the motor vehicle are variable. Variable resistors can have their value altered by movement of a slide or by temperature change.
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Thermistors
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Thermistors are semi-conductor resistors. Their resistance changes according to their temperature and they are used to control many electrical items in the automobile.
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Transistors
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The 2 types of transistor are npn and pnp. In each type, the centre region is always the base. The outer regions are the collector, and the emitter. Transistors are used as switches, and to amplify currents.
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Avalanche diodes
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An avalanche diode is a silicon diode that is designed to break down and conduct at a specified reverse bias voltage.
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Transient voltage suppression diodes
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A transient system is a short-lived oscillation in a system caused by a sudden change of voltage, current or load.
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Zener diodes
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A Zener diode contains a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material.
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P-n junctions
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A p-n junction is formed by combining N-type and P-type semiconductors together in very close contact.
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Superconductors
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Superconductivity is caused by a force of attraction between certain conduction electrons arising from the exchange of phonons, which causes the conduction electrons to exhibit a superfluid phase composed of correlated pairs of electrons.
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| Thyristor |
The thyristor is a solid-state semiconductor device similar to a diode, with an extra terminal which is used to turn it on. |
